Ventilator Gas Valve Control Using Predictive Feedforward
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Solution Overview
Problem
In medical devices, the regulation of gas mixtures for patients is hindered by inaccurate and slow oxygen concentration measurement, leading to delays in supplying the correct amount of oxygen at the correct time.
Innovation Solution
A control unit for ventilators that uses a combination of a feedforward component with a predicted gas flow setpoint value and a correction regulator component to accurately control the gas valve, incorporating patient flow models and exhalation volumes to adjust gas flow based on ventilation situations and respiration phases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a control loop with oxygen concentration measurement is used to regulate gas flow, then the gas composition can be regulated, but the measurement is inaccurate and slow causing delays in oxygen delivery
Solution Approach 1:
The patent calculates a predicted gas flow setpoint value in advance based on patient data, ventilation parameters, and gas mixture composition before actual gas delivery. This preliminary calculation provides a feedforward control signal that anticipates the required oxygen flow, eliminating the need to wait for slow concentration measurements while ensuring accurate oxygen delivery timing
Solution Approach 2:
The patent introduces an intermediary calculation model that computes the predicted gas flow setpoint value by combining patient flow model results with gas mixture composition data. This intermediary computation acts as a bridge between available patient/ventilation data and the required gas valve control, providing accurate oxygen flow prediction without relying on slow direct concentration measurements
2Productivity
If a feedforward component with predicted gas flow setpoint value is used, then the speed and precision of gas regulation is enhanced, but the device complexity increases
Solution Approach 1:
The control unit integrates multiple functions into a single predictive calculation module that simultaneously processes patient flow model results, gas mixture composition data, and ventilation parameters to generate the predicted gas flow setpoint value. This multi-functional approach enhances regulation speed while minimizing the increase in device complexity by consolidating computational tasks
3Manufacturing precision
If correction regulator component and feedforward component are combined, then the accuracy of gas concentration control is improved, but the control system complexity increases
Solution Approach 1:
The patent merges the correction regulator component and feedforward component into a unified control mechanism where the predicted gas flow setpoint value serves as the input for both components. The feedforward component uses the predicted value for anticipatory control, while the correction regulator component compares actual concentration measurements with the predicted value for error correction. This merging approach improves gas concentration control accuracy while managing system complexity through integrated design
Data Source
AI summary
A method and a control unit for executing the method. The method is a method for regulating a gas flow of at least one first gas to be admixed to at least one second gas. The method comprises at least one method step of a control of a gas valve. At least one manipulated variable for the control of the gas valve is determined from at least one correction regulator component and at least one feedforward component, the input variable of the feedforward component being a predicted gas flow setpoint value of the first gas.